Re: Aw: Re: [RFC v1 5/5] arm64: dts: mediatek: Add mt7986 based Bananapi R3 Mini

AngeloGioacchino Del Regno
2024-05-09T10:11:03Z

Il 08/05/24 20:25, Frank Wunderlich ha scritto:
> Hi
>
>> Gesendet: Dienstag, 07. Mai 2024 um 15:35 Uhr
>> Von: "AngeloGioacchino Del Regno" <angelogioacchino.delregno@collabora.com>
>>
>> Il 06/05/24 18:00, Frank Wunderlich ha scritto:
>
>>>>> + fan: pwm-fan {
>>>>> + compatible = "pwm-fan";
>>>>> + #cooling-cells = <2>;
>>>>> + /* cooling level (0, 1, 2) - pwm inverted */
>>>>> + cooling-levels = <255 96 0>;
>>>>
>>>> Did you try to actually invert the PWM?
>>>>
>>>> Look for PWM_POLARITY_INVERTED ;-)
>>>
>>> Mtk pwm driver does not support it
>>>
>>> https://elixir.bootlin.com/linux/latest/source/drivers/pwm/pwm-mediatek.c#L211
>>>
>>
>> You're right, sorry - I confused the general purpose PWM controller with the
>> rather specific DISP_PWM controller (which does support polarity inversion).
>>
>> It's good - but I'd appreciate if you can please add a comment stating that
>> the PWM values are inverted in SW because the controller does *not* support
>> polarity inversion... so that next time someone looks at this will immediately
>> understand what's going on and why :-)
>
> so i would change comment like this:
>
> /* cooling level (0, 1, 2)
> * signal is inverted on board
> * mtk pwm driver does not support
> * PWM_POLARITY_INVERTED */
>

There you go:

/*
* The signal is inverted on this board and the general purpose
* PWM HW IP in this SoC does not support polarity inversion.
*/
/* Cooling level < 0 1 2> */
cooling-levels = <255 96 0>;

>>>>> + pwms = <&pwm 0 10000>;
>>>>> + status = "okay";
>>>>> + };
>>>>> +
>>>>> + phy14: ethernet-phy@14 {
> ...
>>>>> + interrupts-extended = <&pio 48 IRQ_TYPE_EDGE_FALLING>;
>>>>> + reset-gpios = <&pio 49 GPIO_ACTIVE_LOW>;
>>>>> + reset-assert-us = <10000>;
>>>>> + reset-deassert-us = <20000>;
>>>>> + phy-mode = "2500base-x";
>>>>> + full-duplex;
>>>>> + pause;
>>>>> + airoha,pnswap-rx;
>>>>> +
>>>>> + leds {
>>>>> + #address-cells = <1>;
>>>>> + #size-cells = <0>;
>>>>> +
>>>>> + led@0 { /* en8811_a_gpio5 */
>>>>> + reg = <0>;
>>>>> + color = <LED_COLOR_ID_YELLOW>;
>>>>> + function = LED_FUNCTION_LAN;
>>>>> + function-enumerator = <1>;
>>>>
>>>> Why aren't you simply using a label?
>>>
>>> You mean the comment? I can add it of course like for regulators.
>>>
>>
>> I mean in place of the function-enumerator... that's practically used to
>> distinguish between instances, it's not too common to see it, and usually
>> "label" replaces exactly that - just that, instead of a different number,
>> it gets a different name with no (usually) meaningless numbers :-)
>
> as far as i understand using label also makes "function" property useless, after discussing
> this with eric i would drop both on all 4 places by labels like these:
>
> label = "yellow-lan";
> label = "green-lan";
> ...
>
> not sure if we should drop color property too...
>

I'm looking at the leds binding (leds/common.yaml) right now.

My suggestion of using 'label' was actually wrong - and your devicetree was
actually right!!! (apart from the default-trigger that may not work)

Infact, the documentation says, in brief:

- function-enumerator is ignored if label is present
- function doesn't say that gets ignored
- color doesn't say that gets ignored
- label says:
- If not present -> get string from node name
- function-enumerator ignored
- This property is deprecated

...but the 'label' binding does not say 'deprecated: true', which is something
that must be fixed!

So, I'm sorry for the confusion, the noise and the useless loss of time around
this - you can keep the LED nodes as they are, and that's a lesson for the future
me reviewing another node like this one.

P.S.: This shouldn't have been a RFC, as the patches are more than RFC quality!!!

Cheers,
Angelo

>>>>> + default-state = "keep";
>>>>> + linux,default-trigger = "netdev";
>>>>> + };
>>>>> + led@1 { /* en8811_a_gpio4 */
>>>>> + reg = <1>;
>>>>> + color = <LED_COLOR_ID_GREEN>;
>>>>> + function = LED_FUNCTION_LAN;
>>>>> + function-enumerator = <2>;
>>>>> + default-state = "keep";
>>>>> + linux,default-trigger = "netdev";
>>>>> + };
>>>>> + };
>>>>> + };
>>>>> +
>>>>> + phy15: ethernet-phy@15 {
>>>>> + reg = <15>;
>>>>
>>>> Same here.
>>>>
>>>> Cheers,
>>>> Angelo
>
> regards Frank